Suspended CPW Integration on Nanoporous Alumina Interposer for Millimeter Wave Applications

For the next generation of mobile communication, 6G and beyond, 3D integration in the millimeter wave range will play an important role. It allows the integration of the best technology, reducing cost and size, while increasing performance. In this paper, we propose the utilization of a suspended CPW transmission line to interconnect a nanoporous alumina interposer to an embedded fused silica chip. The suspended CPW was fabricated and measured up to 110 GHz with low losses (0.2 dB/mm) and near 50-Ω characteristic impedance.